He doesn't sound like he's got a clue. I've had my Jap import TT for 18 months without a sniff of a problem, and I drove it with hardly any gearbox oil in for about 2 months.
The UK single turbo car was the MKIII and is a comnpletely different beast all together.
I have NEVER had any problems getting parts, and Toyota, although expensive (what dealer isn't) has been pretty helpful, despit not really knowing much aboput the car.
A trusted local garage does all the work to the Supra for a very good price when can't be arsed to do it myself.
You should also note that I have both a manaul NA, and an auto TT and would happily recommend either.
Don't be put off by misinformed people, have a read of stuff on here a decide for yourself.
Oh and PMSL at CJ